1. Field of the Invention
The present invention relates to the manufacture of a substrate provided with a high-definition pattern, such as a substrate provided with a semiconductor circuit, a substrate for a liquid crystal display or a color filter. More particularly, the present invention relates to a cleaning apparatus for cleaning a peripheral part of a substrate, to be employed in a coating process for coating a substrate, such as glass substrate, with a thin film, such as a resist film or a color layer, and a method to be carried out by such a cleaning apparatus.
2. Description of the Related Art
A color filter manufacturing method, for instance, includes a process for forming a chromium film on a substrate, such as a glass substrate, by a vacuum evaporation method or the like; a process for forming a black screening layer of a pattern of stripes or cross stripes by forming a photoresist film on the chromium film, exposing the photoresist film through a photomask to light, subjecting the exposed photoresist film to development, etching the chromium film through the photoresist and removing the photoresist; a process for forming a three-color layer consisting of three color layers, i.e., a R-layer, a G-layer and a B-layer, by coating a first-color photosensitive material on the black screening layer, placing a photomask on the first-color photosensitive material, exposing the first-color photosensitive material through the photomask to light and developing the exposed first-color photosensitive material, and repeating the same process for second-color and third-color layers; and a process for forming a transparent electrode layer by forming an indium tin oxide film (ITO film) on the three-color layer.
In the process for coating a color photosensitive material, the substrate is coated with a coating liquid of a color photosensitive material by a coating method, such as a spin coating method or a slit coating method. Such a coating method drips a coating liquid on a central part of a rotating substrate to spread the coating liquid over the substrate by centrifugal force. As shown in FIG. 4B, when a coating layer 2 is formed on the upper surface of a substrate 1 by this coating method, the coating liquid flows via the edge of the substrate 1 to the lower surface of the substrate 1 and a thick peripheral part 2a is formed on a peripheral part of the upper surface of the substrate 1. If the coating layer 2 having the thick peripheral part 2a is subjected to a developing process, the coating layer remains on the peripheral part of the substrate 1.
Thus, a conventional cleaning method uses a pair of cleaning nozzles 3 disposed opposite to each other so as to correspond to the peripheral part of the substrate 1 provided with the coating layer 2. The cleaning nozzles 3 are moved in the direction of the arrow, spraying a cleaning liquid (developer) on the peripheral part of the substrate 1 to clean the peripheral part of the substrate 1.
When the substrate 1 is cleaned by this conventional cleaning method, however, the substrate 1 splashes about the cleaning liquid sprayed through the cleaning nozzles 3 on the substrate 1 or the tips of the cleaning nozzles 3 touch the substrate 1, so that the cleaning liquid wets the surface of the substrate 1 other than the peripheral part, which is apt to degrade the quality of the high-definition pattern formed on the substrate 1.
The present invention has been made in view of such problems and it is therefore an object of the present invention to provide an apparatus and method for cleaning a peripheral part of a substrate, capable of effectively preventing the splashing of a cleaning liquid and of preventing the degradation of the quality of a high-definition pattern formed on the substrate.
A cleaning apparatus according to an aspect of the present invention for cleaning a peripheral part of a substrate comprises an upper cleaning roller supported for rotation on a base, and including a core member and an elastic porous member covering the circumference of the core member; a lower cleaning roller supported for rotation on the base, including a core member and an elastic porous member covering the circumference of the core member, and capable of holding a peripheral part of the substrate together with the elastic porus member of the upper cleaning roller; a drive mechanism for driving the upper cleaning roller and the lower cleaning roller for rotation; a moving mechanism for moving the upper cleaning roller and the lower cleaning roller relative to the substrate; and a cleaning liquid supply system for supplying a cleaning liquid to at least either the elastic porous member of the upper cleaning roller or that of the lower cleaning roller.
In the cleaning apparatus of the present invention, it is preferable that the cleaning liquid supply system has a cleaning liquid supply pipe to supply the cleaning liquid to the elastic porous members. It is preferable that the core member is a hollow member having a circumferential wall provided with holes, and the cleaning liquid carried by the cleaning liquid supply pipe is supplied through the interior and the holes of the core member to the elastic porous member.
In the cleaning apparatus of the present invention, it is preferable that at least either the upper cleaning roller or the lower cleaning roller is supported for rotation on the base by a rotating shaft, and the cleaning liquid supply system has a cleaning liquid passage formed in the rotating shaft supporting the upper cleaning roller or the lower cleaning roller to supply the cleaning liquid to the elastic porous member. It is preferable that the core member is provided with a connecting passage connected to the cleaning liquid passage of the rotating shaft and opening into the elastic porous member to supply the cleaning liquid carried by the cleaning liquid passage of the rotating shaft to the elastic porous member. It is preferable that the core member is a hollow member having a circumferential wall provided with holes, and the cleaning liquid supplied through the cleaning liquid passage of the rotating shaft is supplied through the interior and the holes of the core member to the elastic porous member.
Preferably, the upper cleaning roller and the lower cleaning roller are interlocked and the drive mechanism is provided with a single drive motor for driving the upper cleaning roller and the lower cleaning roller.
A cleaning method of cleaning a peripheral part of a substrate according to a second aspect of the present invention comprises the steps of holding a peripheral part of a substrate between respective elastic porous members of upper and lower cleaning rollers; supplying a cleaning liquid to at least either the elastic porous member of the upper cleaning roller or that of the lower cleaning roller; and rotating the upper cleaning roller and the lower cleaning roller, moving the upper cleaning roller and the lower cleaning roller relative to the substrate held between the elastic porous members of the upper cleaning roller and the lower cleaning roller.
According to the present invention, the cleaning liquid is supplied to the elastic porous members of the upper and the lower cleaning rollers with the substrate held between the elastic porous members of the upper and the lower cleaning rollers, and the upper and the lower cleaning roller are rotated and moved relative to the substrate. Thus, the splashing of the cleaning liquid can be effectively prevented when removing a thick part on the peripheral part of the substrate of the film formed on the substrate and, consequently, the quality of the high-definition pattern formed on the substrate can be preserved.